Voluntary tic suppression and the normalization of motor cortical beta power in Gilles de la Tourette syndrome: an EEG study

Gilles de la Tourette syndrome (GTS) is a neurological condition characterized by motor and vocal tics. Previous studies suggested that this syndrome is associated with abnormal sensorimotor cortex activity at rest, as well as during the execution of voluntary movements. It has been hypothesized that this abnormality might be interpreted as a form of increased tonic inhibition, probably to suppress tics; however, this hypothesis has not been tested so far. The present study was designed to formally test how voluntary tic suppression in GTS influences the activity of the sensorimotor cortex during the execution of a motor task. We used EEG to record neural activity over the contralateral sensorimotor cortex during a finger movement task in adult GTS patients, in both free ticcing and tic suppression conditions; these data were then compared with those collected during the same task in age‐matched healthy subjects. We focused on the levels of activity in the beta frequency band, which is typically associated with the activation of the motor system, during three different phases: a pre‐movement, a movement, and a post‐movement phase. GTS patients showed decreased levels of beta modulation with respect to the healthy controls, during the execution of the task; however, this abnormal pattern returned to be normal when they were explicitly asked to suppress their tics while moving. This is the first demonstration that voluntary tic suppression in GTS operates through the normalization of the EEG rhythm in the beta frequency range during the execution of a voluntary finger movement.     

Role of the sensorimotor cortex in tourette syndrome using multimodal imaging

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by motor and vocal tics. Most patients describe uncomfortable premonitory sensations preceding the tics and a subjective experience of increased sensitivity to tactile stimuli. These reports indicate that a sensory processing disturbance is an important component of TS together with motor phenomena. Thus, we focused our investigation on the role of the sensorimotor cortex (SMC) in TS using multimodal neuroimaging techniques. We measured the gamma‐aminobutyric acid (GABA)+/Creatine (Cre) ratio in the SMC using GABA ¹H magnetic resonance spectroscopy. We recorded the baseline beta activity in the SMC using magnetoencephalography and correlated GABA+/Cre ratio with baseline beta band power. Finally, we examined the resting state functional connectivity (FC) pattern of the SMC using functional magnetic resonance imaging (fMRI). GABA+/Cre ratio in the SMC did not differ between patients and controls. Correlation between the baseline beta band power and GABA+/Cre ratio was abnormal in patients. The anterior insula showed increased FC with the SMC in patients. These findings suggest that altered limbic input to the SMC and abnormal GABA‐mediated beta oscillations in the SMC may underpin some of the sensorimotor processing disturbances in TS and contribute to tic generation. Hum Brain Mapp 35:5834–5846, 2014. Published 2014. This article is a U.S. Government work and is in the public domain in the USA .     

Pre-movement gating of somatosensory evoked potentials in Tourette syndrome

ObjectiveTourette syndrome (TS) is a neurobehavioral disorder characterized by motor and vocal tics. Simple tics are purposeless involuntary movements that spontaneously resolve during middle adolescence. Complex tics appear to be semi-voluntary movements that may become intractable when associated with obsessive–compulsive disorder (OCD). Sensory tics or urges preceded by tics suggest sensorimotor processing impairment in TS. We aimed to clarify its pathophysiology by exploring the pre-movement gating (attenuation) of somatosensory evoked potentials (SEPs).MethodsWe examined 42 patients (aged 9–48 years), 4 of whom underwent follow-up assessment, along with 19 healthy controls. We defined patients with only simple tics as TS-S and patients with complex tics as TS-C. Pre-movement gating of SEPs was assessed using a previously described method. Frontal N30 (FrN30) amplitudes were compared between pre-movement and resting states. The gating ratio of pre-movement/resting amplitude of the FrN30 component was assessed: the larger the ratio, the less the gating.ResultsThe gating ratio for TS-C patients was larger than that of TS-S patients and healthy controls, but a statistical difference between TS-S and TS-C appeared after 15 years and over (p < 0.001). There were no significant differences in the gating ratio between TS-S patients and healthy controls. The gating ratio was related to the severity of OCD (p < 0.05).ConclusionSensorimotor processing was preserved for simple tics but impaired in complex tics, specifically after middle adolescence. Our study supports an age-dependent dysfunction of both motor and non-motor cortico-striato-thalamo-cortical circuits in complex tics. SEP gating seems promising as a tool for assessing age-dependent sensorimotor disintegration in TS.     

Tourette syndrome: the self under siege

Tourette syndrome is a neurodevelopmental disorder characterized by motor and vocal tics--rapid, repetitive, stereotyped movements or vocalizations. Tourette syndrome typically has a prepubertal onset, and boys are more commonly affected than girls. Symptoms usually begin with transient bouts of simple motor tics. By age 10 years, most children are aware of nearly irresistible somatosensory urges that precede the tics. These urges likely reflect a defect in sensorimotor gating because they intrude into the child's conscious awareness and become a source of distraction and distress. A momentary sense of relief typically follows the completion of a tic. Over the course of hours, tics occur in bouts, with a regular intertic interval. Tics increase during periods of emotional excitement and fatigue. Tics can become "complex" in nature and appear to be purposeful. Tics can be willfully suppressed for brief intervals and can be evoked by the mere mention of them. Tics typically diminish during periods of goal-directed behavior, especially those that involve both heightened attention and fine motor or vocal control, as occur in musical and athletic performances. Over the course of months, tics wax and wane. New tics appear, often in response to new sources of somatosensory irritation, such as the appearance of a persistent vocal tic (a cough) following a cold. Over the course of years, tic severity typically peaks between 8 and 12 years of age. By the end of the second decade of life, many individuals are virtually tic free. Less than 20% of cases continue to experience clinically impairing tics as adults. Tics rarely occur in isolation, and other coexisting conditions--such as behavioral disinhibition, hypersensitivity to a broad range of sensory stimuli, problems with visual motor integration, procedural learning difficulties, attention-deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder, depression, anxiety, and emotional instability--are often a greater source of impairment than the tics themselves. Emerging behavioral treatments of Tourette syndrome are based in part on an understanding of the moment-to-moment experience of somatosensory urges and motor response. With identification of specific genes of major effect and advances in our understanding of the neural circuitry of sensorimotor gating, habit formation, and procedural memory--together with insights from postmortem brain studies, in vivo brain imaging, and electrophysiologic recordings--we might be on the threshold of a deeper understanding of the phenomenology and natural history of Tourette syndrome.     

Neural correlates of altered sensorimotor gating in boys with Tourette Syndrome: A combined EMG/fMRI study

Objectives: It has been hypothesised that altered sensorimotor gating might be a core problem in Tourette Syndrome (TS). However, the underlying neurophysiological mechanisms are elusive. Methods: We applied functional magnetic resonance imaging (fMRI) to investigate the neural correlates of altered sensorimotor gating by means of prepulse inhibition (PPI) in 22 boys with TS and 22 healthy boys using tactile PPI. The electromyography of the startle response was recorded simultaneously to the acquisition of the fMRI images. Results: As expected, PPI of the startle response was reduced in boys with TS compared to the healthy boys. We found decreased PPI-related blood oxygen level-dependent (BOLD) activity in boys with TS in the middle frontal gyrus, postcentral gyrus, superior parietal cortex, cingulate gyrus and caudate body. In boys with TS PPI of the startle response was positively correlated to PPI-related BOLD activity in the superior parietal cortex. Conclusions: Our findings indicate that deficient sensorimotor gating in boys with TS is associated with reduced recruitment of brain regions responsible for the higher-order integration of somatosensory stimuli. Due to our strict sample selection we were able to reduce confounding by neural adaptation processes, long-term medication, gender or comorbidities.     

Temporo-parietal dysfunction in Tourette syndrome: Insights from an fMRI study of Theory of Mind

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by tics, repetitive movements and vocalizations which are prompted by a sensory-cognitive premonitory urge. Complex tics include environmentally dependent social behaviors such as echoing of other people's speech and actions. Recent studies have suggested that adults with TS can show differences to controls in Theory of Mind (ToM): reasoning about mental states (e.g. beliefs, emotions). In this study, twenty-five adults with uncomplicated TS (no co-morbid disorders, moderate tic severity), and twenty-five healthy age and gender matched controls were scanned with fMRI during an established ToM task. Neural activity was contrasted across ToM trials involving reasoning about false-belief, and matched trials requiring judgments about physical states rather than mental states. Contrasting task conditions uncovered differential fMRI activation in TS during ToM involving the right temporo-parietal junction (TPJ), right amygdala and posterior cingulate. Further analysis revealed that activity within the right TPJ as localised by this task covaried with the severity of symptoms including echophenomena, impulse control problems and premonitory urges in TS. Amygdala activation was also linked to premonitory urges, while activity in the left TPJ during ToM was linked to ratings of non-obscene socially inappropriate symptoms. These findings indicate that patients with TS exhibit atypical functional activation within key neural substrates involved in ToM. More generally, our data could highlight an important role for TPJ dysfunction in driving compulsive behaviors.     

Premonitory urges and repetitive behaviours in adult patients with Tourette syndrome

Tourette syndrome (TS) is a neurodevelopmental disorder characterised by multiple motor and phonic tics, which are associated with sensory symptoms (premonitory urges). Little is known about the nature of the subjective urges and repetitive behaviours which are intrinsic to TS. This study assessed the relationship between specific urges and repetitive behaviours in 108 consecutive adult patients recruited at a specialist TS Clinic. Analysis of self-report measures of sensory symptoms (Premonitory Urge for Tics Scale) and repetitive behaviours (Motor tic, Obsessions and compulsions, Vocal tic Evaluation Survey) showed that different types of urges are associated with simple/complex tics and obsessive–compulsive symptoms.     

Imaging evidence for anatomical disturbances and neuroplastic compensation in persons with Tourette syndrome

BackgroundTourette syndrome (TS) is a disorder of chronic motor and vocal tics that begins in childhood.MethodsA systematic Medline search was conducted to identify existing anatomical imaging studies in persons with TS.ResultsThirty studies were identified, and their methods and findings were reviewed. Findings of reduced caudate volumes across the life span and thinning of sensorimotor cortices that is proportional with tic severity in children with TS implicate these regions in the genesis of tics. Hypertrophy of limbic and prefrontal cortices and a smaller corpus callosum accompany fewer symptoms in children with TS, likely representing an activity-dependent plasticity within these regions that help to modulate tic severity.ConclusionAlthough existing studies differ with respect to sample size, gender composition, quality of clinical characterization, pulse sequences, and methods of image analysis, the preponderance of evidence suggests that disturbances in the development of the motor portions of cortical–subcortical circuits likely predispose to the development TS and that neuroplastic changes in control systems of the brain help to modulate the severity of symptom expression. These findings from cross-sectional studies require confirmation in more representative populations within longitudinal studies.     

The pharmacology of Tourette syndrome

Tourette syndrome (TS) is a chronic neuropsychiatric disorder characterised by multiple motor and vocal tics, plus associated behavioural symptoms. Tics are defined as sudden, rapid, repetitive non-rhythmic movements (motor tics) or vocalisations (vocal tics). Tics are distressing symptoms and can lead to considerable disruption to social functioning and quality of life. Converging evidence from different lines of research suggests that the pathophysiology of TS involves altered dopaminergic transmission in the cortico-striatal–thalamo-cortical circuits, along with other neurotransmitter systems. Pharmacotherapy is currently the treatment of choice in patients with moderate-to-severe tics, particularly when associated with deterioration in social, occupational or academic performance. This review will focus on the recent evidence base supporting the use of different medication classes for the treatment of tics in TS. The recent publication of the European and Canadian guidelines on the management of TS are based on experts’ consensus and highlight the need for randomised controlled trials, especially with regards to newly developed pharmacological agents.     

Cannabinoids: possible role in patho-physiology and therapy of Gilles de la Tourette syndrome

High densities of cannabinoid receptors were found in the basal ganglia and hippocampus, indicating a putative functional role of cannabinoids in movement and behaviour. Anecdotal reports suggested beneficial effects of marijuana in Tourette's syndrome (TS). We therefore interviewed 64 TS patients with regard to use of marijuana and its influence on TS symptomatology. Of 17 patients (27%) who reported prior use of marijuana, 14 subjects (82%) experienced a reduction or complete remission of motor and vocal tics and an amelioration of premonitory urges and obsessive-compulsive symptoms. Our results provide more evidence that marijuana improves tics and behavioural disorders in TS. It can be speculated that cannabinoids might act through specific receptors, and that the cannabinoid system might play a major role in TS pathology.     

Imaging evidence for anatomical disturbances and neuroplastic compensation in persons with Tourette syndrome

Background

Tourette syndrome (TS) is a disorder of chronic motor and vocal tics that begins in childhood.

Methods

A systematic Medline search was conducted to identify existing anatomical imaging studies in persons with TS.

Results

Thirty studies were identified, and their methods and findings were reviewed. Findings of reduced caudate volumes across the life span and thinning of sensorimotor cortices that is proportional with tic severity in children with TS implicate these regions in the genesis of tics. Hypertrophy of limbic and prefrontal cortices and a smaller corpus callosum accompany fewer symptoms in children with TS, likely representing an activity-dependent plasticity within these regions that help to modulate tic severity.

Conclusion

Although existing studies differ with respect to sample size, gender composition, quality of clinical characterization, pulse sequences, and methods of image analysis, the preponderance of evidence suggests that disturbances in the development of the motor portions of cortical–subcortical circuits likely predispose to the development TS and that neuroplastic changes in control systems of the brain help to modulate the severity of symptom expression. These findings from cross-sectional studies require confirmation in more representative populations within longitudinal studies.     

Combining tract‐ and atlas‐based analysis reveals microstructural abnormalities in early Tourette syndrome children

Tourette syndrome (TS) is a neurological disorder that causes uncontrolled repetitive motor and vocal tics in children. Examining the neural basis of TS churned out different research studies that advanced our understanding of the brain pathways involved in its development. Particularly, growing evidence points to abnormalities within the fronto‐striato‐thalamic pathways. In this study, we combined Tract‐Based Spatial Statistics (TBSS) and Atlas‐based regions of interest (ROI) analysis approach, to investigate the microstructural diffusion changes in both deep and superficial white matter (SWM) in TS children. We then characterized the altered microstructure of white matter in 27 TS children in comparison with 27 age‐ and gender‐matched healthy controls. We found that fractional anisotropy (FA) decreases and radial diffusivity (RD) increases in deep white matter (DWM) tracts in cortico‐striato‐thalamo‐cortical (CSTC) circuit as well as SWM. Furthermore, we found that lower FA values and higher RD values in white matter regions are correlated with more severe tics, but not tics duration. Besides, we also found both axial diffusivity and mean diffusivity increase using Atlas‐based ROI analysis. Our work may suggest that microstructural diffusion changes in white matter is not only restricted to the gray matter of CSTC circuit but also affects SWM within the primary motor and somatosensory cortex, commissural and association fibers. Hum Brain Mapp 37:1903–1919, 2016. © 2016 Wiley Periodicals, Inc.     

Tics and Tourette syndrome: clinical evaluation of 44 cases

We evaluated 44 patients with tics and Tourette's syndrome (TS) emphasising the age of onset of symptoms, sex, classification and localization of tics, associated symptoms and signs and comorbidities. Thirty-three patients (75.2%) had TS defined criteria whereas 10 (22.7%) had chronic motor and/or vocal tics. Simple motor tics were found in 43 cases (97.7%), mainly affecting the eyes (43.2%), mouth (43.2%), face (34.1%). Simple vocal tics occurred in 33 (75%). Coprolalia was found in just 6 cases (13.6%) and copropraxia in just 2 (4.5%). Obsessive compulsive disorder and/or symptoms were found in 26 cases (59.1%) and attention deficit in 17 (38.6%). Eighteen patients (40.9%) had other disorders, such as alcoholism, tabagism, drug abuse, affective disorders, anxiety, sleep and learning disorders. The data obtained are similar to those found by other authors. We highlight the low frequency of coprolalia, as well as the associated neuropsychiatric disorders.     

Prevalence of tic disorders and Tourette syndrome in a Swedish school population

The aim of the study was to find the epidemiological distribution of tic disorders and Tourette syndrome (TS) in Swedish school children aged 7 to 15 years. A total population of 4,479 children and their parents were asked to fill in a questionnaire covering both motor and vocal tics. A three-stage procedure was used: screening, interview, and clinical investigation. Two hundred and ninety-seven children (190 males, 107 females) were found to have tics. TS, according to DSM-IV criteria, was found in 0.6% of the total population, another 0.8% had chronic motor tics, and 0.5% had chronic vocal tics. Further, 4.8% of the children had transient tics. All together 6.6% of 7- to 15-year-old children currently had or had experienced some kind tic disorder during the last year. Prevalence of different tic disorders was higher among younger children and in males, and was highly associated with school dysfunction. The prevalence of TS was higher than was previously thought but other tic disorders were more common in this childhood population.     

Complex phonic tic and disinhibition in Tourette syndrome: case report

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by a combination of multiple motor tics and at least one phonic tic. TS patients often have associated behavioral abnormalities such as obsessive compulsive disorder, attention deficit and hyperactive disorder. Coprolalia, defined as emission of obscenities or swearing, is one type of complex vocal tic, present in 8% to 26% of patients. The pathophysiology of coprolalia and other complex phonic tics remains ill-defined. We report a patient whose complex phonic tic was characterized by repetitively saying "breast cancer" on seeing the son of aunt who suffered from this condition. The patient was unable to suppress the tic and did not meet criteria for obsessive compulsive disorder. The phenomenology herein described supports the theory that complex phonic tics result from disinhibition of the loop connecting the basal ganglia with the limbic cortex.     

Altered motor network recruitment during finger tapping in boys with Tourette syndrome

In Tourette syndrome (TS), not only the tics but also the findings on deficits in motor performance indicate motor system alterations. But our knowledge about the pathophysiology of the motor system in TS is still limited. To better understand the neuronal correlates of motor performance in TS, 19 treatment‐naïve boys [age 12.5 (SD 1.4) years] with TS without comorbid symptomatology were compared to an age‐matched healthy control group [n = 16; age 12.9 (SD 1.6) years] in regard to brain activation during right‐hand index finger tapping by means of functional magnetic resonance imaging. Group differences were found mainly in the left (contralateral) precentral gyrus, which was less activated in boys suffering from TS and in caudate nucleus as well as in medial prefrontal cortex, which was more activated compared to healthy boys. These results show that even in the first years after the onset of the disorder, an altered brain network of motor performance is recruited. These alterations in brain regions frequently associated with TS are probably based on functional changes, which are discussed in terms of early compensatory mechanisms of the motor execution network. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.     

Dystonic tics in patients with Tourette's syndrome

Dystonic tics, in contrast to clonic tics, are relatively slow and temporarily sustained twisting, pulling, or squeezing movements producing briefly maintained abnormal postures. Because dystonic tics often present diagnostic difficulties, we studied these motor tics in 156 patients with Tourette's syndrome (TS). In addition to clonic motor and vocal/phonic tics, seen in all patients, 89 (57%) of them exhibited one or more dystonic tics. The most common dystonic tics were oculogyric deviations (43 patients), blepharospasm (23), and dystonic neck movements (11). Blinking (110) and facial twitching (86) were the most common clonic tics. Except for possibly a greater familial occurrence, a higher frequency of previous head trauma, and associated attention deficit disorder, the group of patients with dystonic tics did not significantly differ in any of the major clinical variables from those TS patients without dystonic tics. We conclude that dystonic tics are typical motor manifestations of TS and that patients with these motor tics are not different from those with more typical clonic tics.     

The relationship between putamen-SMA functional connectivity and sensorimotor abnormality in ESRD patients

The basal ganglia (BG) are composed of several nuclei involved in neural processing associated with integration of sensory and motor information. Recent neuroimaging studies implicated its key role in control of voluntary motor function. As the sensorimotor abnormality is common among the end-stage renal disease (ESRD) population, in the current study, we aimed to investigate the abnormal structure and functional connectivity patterns of BG in ESRD patients. Twenty-nine ESRD and twenty-nine age and gender-matched healthy controls (HC) were enrolled to compare the volume of the subsets in the BG (e.g., caudate nucleus, putamen and globus pallidus) by using the VBM analysis; resting-state functional connectivity was analyzed by a seed-based method. Compared with the HC group, ESRD patients had a smaller volume in the right putamen. Taking the right putamen as a seed region, we further found reduced functional connectivity in patients mainly between the putamen and supplementary motor area (SMA), insula, posterior mid-cingulate gyrus, and primary motor cortex. In ESRD group, the severity score of restless legs syndrome was negatively correlated with putamen-SMA functional connectivity, while the hemoglobin level was positively correlated with functional connectivity degree between the putamen and SMA. Our results revealed an abnormal volume of the putamen and its decreased functional connectivity patterns during resting state in ESRD with sensorimotor abnormalities. These preliminary results indicated that the decreased functional connectivity in putamen-SMA was associated with sensorimotor abnormalities, and anemia was correlated with this abnormal functional pattern in ESRD patients.     

Group Work in Young People with Tourette Syndrome

Gilles de la Tourette Syndrome (TS) is characterised by motor and vocal tics, although it is often associated with learning, emotional or behavioural problems that tend to account for most of the impairment experienced. Recognising, naming and learning to cope with the range of difficulties arising in TS is an important part of treatment. Group working was used as a way of helping young people understand and deal with TS. Sessions focused on managing tics, building self-esteem, learning and bullying, anger management and obsessive-compulsive symptoms.